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	$250.29	11.352%	$278.7029	$278.70	$278.70	$278.70
Purchase #2	$183.30	7.299%	$196.6791	$196.68	$196.70	$196.70
Purchase #3	$62.27	7.719%	$67.0766	$67.08	$67.10	$67.10
Purchase #4	$83.81	9.772%	$91.9999	$92.00	$92.00	$92.00
Purchase #5	$165.82	11.666%	$185.1646	$185.16	$185.15	$185.20
Purchase #6	$145.35	8.400%	$157.5594	$157.56	$157.55	$157.60
Purchase #7	$53.57	11.729%	$59.8532	$59.85	$59.85	$59.90
7 purchase totals =	$944.41		$1,037.0357	$1,037.03	$1,037.05	$1,037.20