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	$71.56	6.323%	$76.0847	$76.08	$76.10	$76.10
Purchase #2	$142.57	7.499%	$153.2613	$153.26	$153.25	$153.30
Purchase #3	$107.44	3.562%	$111.267	$111.27	$111.25	$111.30
Purchase #4	$73.98	11.512%	$82.4966	$82.50	$82.50	$82.50
Purchase #5	$178.77	3.564%	$185.1414	$185.14	$185.15	$185.10
Purchase #6	$249.61	9.486%	$273.288	$273.29	$273.30	$273.30
Purchase #7	$249.96	6.506%	$266.2224	$266.22	$266.20	$266.20
7 purchase totals =	$1,073.89		$1,147.7614	$1,147.76	$1,147.75	$1,147.80