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	$188.59	7.251%	$202.2647	$202.26	$202.25	$202.30
Purchase #2	$53.45	6.731%	$57.0477	$57.05	$57.05	$57.00
Purchase #3	$150.41	11.633%	$167.9072	$167.91	$167.90	$167.90
Purchase #4	$172.56	3.870%	$179.2381	$179.24	$179.25	$179.20
Purchase #5	$163.27	4.787%	$171.0857	$171.09	$171.10	$171.10
Purchase #6	$122.59	3.798%	$127.246	$127.25	$127.25	$127.20
Purchase #7	$116.89	7.631%	$125.8099	$125.81	$125.80	$125.80
7 purchase totals =	$967.76		$1,030.5993	$1,030.61	$1,030.60	$1,030.50