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	$243.27	7.727%	$262.0675	$262.07	$262.05	$262.10
Purchase #2	$68.55	8.692%	$74.5084	$74.51	$74.50	$74.50
Purchase #3	$222.48	9.476%	$243.5622	$243.56	$243.55	$243.60
Purchase #4	$150.31	4.363%	$156.868	$156.87	$156.85	$156.90
Purchase #5	$147.63	11.431%	$164.5056	$164.51	$164.50	$164.50
Purchase #6	$130.56	8.578%	$141.7594	$141.76	$141.75	$141.80
Purchase #7	$117.71	10.486%	$130.0531	$130.05	$130.05	$130.10
7 purchase totals =	$1,080.51		$1,173.3242	$1,173.33	$1,173.25	$1,173.50