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	$92.70	4.385%	$96.7649	$96.76	$96.75	$96.80
Purchase #2	$35.59	8.488%	$38.6109	$38.61	$38.60	$38.60
Purchase #3	$149.91	6.203%	$159.2089	$159.21	$159.20	$159.20
Purchase #4	$197.37	8.116%	$213.3885	$213.39	$213.40	$213.40
Purchase #5	$18.59	12.210%	$20.8598	$20.86	$20.85	$20.90
Purchase #6	$248.57	6.258%	$264.1255	$264.13	$264.15	$264.10
Purchase #7	$229.30	4.801%	$240.3087	$240.31	$240.30	$240.30
7 purchase totals =	$972.03		$1,033.2672	$1,033.27	$1,033.25	$1,033.30