Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$174.28	10.233%	$192.1141	$192.11	$192.10	$192.10
Purchase #2	$131.42	10.441%	$145.1416	$145.14	$145.15	$145.10
Purchase #3	$206.45	7.496%	$221.9255	$221.93	$221.95	$221.90
Purchase #4	$108.96	13.381%	$123.5399	$123.54	$123.55	$123.50
Purchase #5	$122.38	7.324%	$131.3431	$131.34	$131.35	$131.30
Purchase #6	$247.88	8.512%	$268.9795	$268.98	$269.00	$269.00
Purchase #7	$250.96	13.516%	$284.8798	$284.88	$284.90	$284.90
7 purchase totals =	$1,242.33		$1,367.9235	$1,367.92	$1,368.00	$1,367.80