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	$195.78	7.509%	$210.4811	$210.48	$210.50	$210.50
Purchase #2	$211.78	13.609%	$240.6011	$240.60	$240.60	$240.60
Purchase #3	$34.80	7.282%	$37.3341	$37.33	$37.35	$37.30
Purchase #4	$134.30	10.163%	$147.9489	$147.95	$147.95	$147.90
Purchase #5	$97.94	7.479%	$105.2649	$105.26	$105.25	$105.30
Purchase #6	$73.34	12.483%	$82.495	$82.50	$82.50	$82.50
Purchase #7	$176.58	7.586%	$189.9754	$189.98	$190.00	$190.00
7 purchase totals =	$924.52		$1,014.1005	$1,014.10	$1,014.15	$1,014.10