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	$49.90	7.724%	$53.7543	$53.75	$53.75	$53.80
Purchase #2	$198.38	8.432%	$215.1074	$215.11	$215.10	$215.10
Purchase #3	$91.77	10.595%	$101.493	$101.49	$101.50	$101.50
Purchase #4	$243.98	8.395%	$264.4621	$264.46	$264.45	$264.50
Purchase #5	$176.80	13.277%	$200.2737	$200.27	$200.25	$200.30
Purchase #6	$59.59	7.700%	$64.1784	$64.18	$64.20	$64.20
Purchase #7	$103.90	10.390%	$114.6952	$114.70	$114.70	$114.70
7 purchase totals =	$924.32		$1,013.9641	$1,013.96	$1,013.95	$1,014.10