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	$148.66	4.503%	$155.3542	$155.35	$155.35	$155.40
Purchase #2	$72.85	4.512%	$76.137	$76.14	$76.15	$76.10
Purchase #3	$54.74	10.660%	$60.5753	$60.58	$60.60	$60.60
Purchase #4	$123.33	3.362%	$127.4764	$127.48	$127.50	$127.50
Purchase #5	$242.72	10.826%	$268.9969	$269.00	$269.00	$269.00
Purchase #6	$86.43	3.398%	$89.3669	$89.37	$89.35	$89.40
Purchase #7	$5.26	13.218%	$5.9553	$5.96	$5.95	$6.00
7 purchase totals =	$733.99		$783.8620	$783.88	$783.90	$784.00