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	$59.55	3.721%	$61.7659	$61.77	$61.75	$61.80
Purchase #2	$68.37	5.762%	$72.3095	$72.31	$72.30	$72.30
Purchase #3	$194.67	8.429%	$211.0787	$211.08	$211.10	$211.10
Purchase #4	$184.43	13.478%	$209.2875	$209.29	$209.30	$209.30
Purchase #5	$94.68	10.753%	$104.8609	$104.86	$104.85	$104.90
Purchase #6	$135.65	9.197%	$148.1257	$148.13	$148.15	$148.10
Purchase #7	$227.93	7.872%	$245.8726	$245.87	$245.85	$245.90
7 purchase totals =	$965.28		$1,053.3008	$1,053.31	$1,053.30	$1,053.40