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	$83.74	4.360%	$87.3911	$87.39	$87.40	$87.40
Purchase #2	$90.84	5.630%	$95.9543	$95.95	$95.95	$96.00
Purchase #3	$189.76	4.498%	$198.2954	$198.30	$198.30	$198.30
Purchase #4	$101.38	3.126%	$104.5491	$104.55	$104.55	$104.50
Purchase #5	$236.39	11.474%	$263.5134	$263.51	$263.50	$263.50
Purchase #6	$35.29	5.498%	$37.2302	$37.23	$37.25	$37.20
Purchase #7	$225.95	12.662%	$254.5598	$254.56	$254.55	$254.60
7 purchase totals =	$963.35		$1,041.4933	$1,041.49	$1,041.50	$1,041.50