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	$162.26	5.422%	$171.0577	$171.06	$171.05	$171.10
Purchase #2	$29.82	13.654%	$33.8916	$33.89	$33.90	$33.90
Purchase #3	$103.27	9.696%	$113.2831	$113.28	$113.30	$113.30
Purchase #4	$224.83	8.412%	$243.7427	$243.74	$243.75	$243.70
Purchase #5	$184.50	11.616%	$205.9315	$205.93	$205.95	$205.90
Purchase #6	$229.57	8.137%	$248.2501	$248.25	$248.25	$248.30
Purchase #7	$61.77	4.703%	$64.675	$64.68	$64.70	$64.70
7 purchase totals =	$996.02		$1,080.8317	$1,080.83	$1,080.90	$1,080.90