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	$86.73	6.474%	$92.3449	$92.34	$92.35	$92.30
Purchase #2	$211.35	5.401%	$222.765	$222.77	$222.75	$222.80
Purchase #3	$197.40	11.592%	$220.2826	$220.28	$220.30	$220.30
Purchase #4	$66.29	5.843%	$70.1633	$70.16	$70.15	$70.20
Purchase #5	$178.41	4.512%	$186.4599	$186.46	$186.45	$186.50
Purchase #6	$107.62	3.222%	$111.0875	$111.09	$111.10	$111.10
Purchase #7	$156.85	5.320%	$165.1944	$165.19	$165.20	$165.20
7 purchase totals =	$1,004.65		$1,068.2976	$1,068.29	$1,068.30	$1,068.40