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	$88.42	4.162%	$92.1	$92.10	$92.10	$92.10
Purchase #2	$159.50	6.160%	$169.3252	$169.33	$169.35	$169.30
Purchase #3	$168.27	4.160%	$175.27	$175.27	$175.25	$175.30
Purchase #4	$73.30	4.221%	$76.394	$76.39	$76.40	$76.40
Purchase #5	$41.72	8.136%	$45.1143	$45.11	$45.10	$45.10
Purchase #6	$250.26	3.186%	$258.2333	$258.23	$258.25	$258.20
Purchase #7	$191.85	9.144%	$209.3928	$209.39	$209.40	$209.40
7 purchase totals =	$973.32		$1,025.8296	$1,025.82	$1,025.85	$1,025.80