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	$95.89	7.575%	$103.1537	$103.15	$103.15	$103.20
Purchase #2	$225.41	13.661%	$256.2033	$256.20	$256.20	$256.20
Purchase #3	$31.51	5.664%	$33.2947	$33.29	$33.30	$33.30
Purchase #4	$167.65	9.177%	$183.0352	$183.04	$183.05	$183.00
Purchase #5	$37.96	8.397%	$41.1475	$41.15	$41.15	$41.10
Purchase #6	$237.79	11.333%	$264.7387	$264.74	$264.75	$264.70
Purchase #7	$165.29	5.740%	$174.7776	$174.78	$174.80	$174.80
7 purchase totals =	$961.50		$1,056.3507	$1,056.35	$1,056.40	$1,056.30