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	$188.67	4.310%	$196.8017	$196.80	$196.80	$196.80
Purchase #2	$54.42	8.486%	$59.0381	$59.04	$59.05	$59.00
Purchase #3	$170.90	8.178%	$184.8762	$184.88	$184.90	$184.90
Purchase #4	$224.45	8.814%	$244.233	$244.23	$244.25	$244.20
Purchase #5	$89.32	8.225%	$96.6666	$96.67	$96.65	$96.70
Purchase #6	$8.72	9.666%	$9.5629	$9.56	$9.55	$9.60
Purchase #7	$212.35	7.662%	$228.6203	$228.62	$228.60	$228.60
7 purchase totals =	$948.83		$1,019.7988	$1,019.80	$1,019.80	$1,019.80